/**
 * @license
 * Copyright (c) 2013, Brandon Jones, Colin MacKenzie IV. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

import { GLMAT_ARRAY_TYPE } from './common';

/**
 * @class 2x3 Matrix
 * @name mat2d
 *
 * @description
 * A mat2d contains six elements defined as:
 * <pre>
 * [a, c, tx,
 *  b, d, ty]
 * </pre>
 * This is a short form for the 3x3 matrix:
 * <pre>
 * [a, c, tx,
 *  b, d, ty,
 *  0, 0, 1]
 * </pre>
 * The last row is ignored so the array is shorter and operations are faster.
 */

var mat2d = {};

/**
 * Creates a new identity mat2d
 *
 * @returns {mat2d} a new 2x3 matrix
 */
mat2d.create = function() {
    var out = new GLMAT_ARRAY_TYPE(6);
    out[0] = 1;
    out[1] = 0;
    out[2] = 0;
    out[3] = 1;
    out[4] = 0;
    out[5] = 0;
    return out;
};

/**
 * Creates a new mat2d initialized with values from an existing matrix
 *
 * @param {mat2d} a matrix to clone
 * @returns {mat2d} a new 2x3 matrix
 */
mat2d.clone = function(a) {
    var out = new GLMAT_ARRAY_TYPE(6);
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    out[4] = a[4];
    out[5] = a[5];
    return out;
};

/**
 * Copy the values from one mat2d to another
 *
 * @param {mat2d} out the receiving matrix
 * @param {mat2d} a the source matrix
 * @returns {mat2d} out
 */
mat2d.copy = function(out, a) {
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    out[4] = a[4];
    out[5] = a[5];
    return out;
};

/**
 * Set a mat2d to the identity matrix
 *
 * @param {mat2d} out the receiving matrix
 * @returns {mat2d} out
 */
mat2d.identity = function(out) {
    out[0] = 1;
    out[1] = 0;
    out[2] = 0;
    out[3] = 1;
    out[4] = 0;
    out[5] = 0;
    return out;
};

/**
 * Inverts a mat2d
 *
 * @param {mat2d} out the receiving matrix
 * @param {mat2d} a the source matrix
 * @returns {mat2d} out
 */
mat2d.invert = function(out, a) {
    var aa = a[0], ab = a[1], ac = a[2], ad = a[3],
        atx = a[4], aty = a[5];

    var det = aa * ad - ab * ac;
    if(!det){
        return null;
    }
    det = 1.0 / det;

    out[0] = ad * det;
    out[1] = -ab * det;
    out[2] = -ac * det;
    out[3] = aa * det;
    out[4] = (ac * aty - ad * atx) * det;
    out[5] = (ab * atx - aa * aty) * det;
    return out;
};

/**
 * Calculates the determinant of a mat2d
 *
 * @param {mat2d} a the source matrix
 * @returns {Number} determinant of a
 */
mat2d.determinant = function (a) {
    return a[0] * a[3] - a[1] * a[2];
};

/**
 * Multiplies two mat2d's
 *
 * @param {mat2d} out the receiving matrix
 * @param {mat2d} a the first operand
 * @param {mat2d} b the second operand
 * @returns {mat2d} out
 */
mat2d.multiply = function (out, a, b) {
    var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4], a5 = a[5],
        b0 = b[0], b1 = b[1], b2 = b[2], b3 = b[3], b4 = b[4], b5 = b[5];
    out[0] = a0 * b0 + a2 * b1;
    out[1] = a1 * b0 + a3 * b1;
    out[2] = a0 * b2 + a2 * b3;
    out[3] = a1 * b2 + a3 * b3;
    out[4] = a0 * b4 + a2 * b5 + a4;
    out[5] = a1 * b4 + a3 * b5 + a5;
    return out;
};

/**
 * Alias for {@link mat2d.multiply}
 * @function
 */
mat2d.mul = mat2d.multiply;


/**
 * Rotates a mat2d by the given angle
 *
 * @param {mat2d} out the receiving matrix
 * @param {mat2d} a the matrix to rotate
 * @param {Number} rad the angle to rotate the matrix by
 * @returns {mat2d} out
 */
mat2d.rotate = function (out, a, rad) {
    var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4], a5 = a[5],
        s = Math.sin(rad),
        c = Math.cos(rad);
    out[0] = a0 *  c + a2 * s;
    out[1] = a1 *  c + a3 * s;
    out[2] = a0 * -s + a2 * c;
    out[3] = a1 * -s + a3 * c;
    out[4] = a4;
    out[5] = a5;
    return out;
};

/**
 * Scales the mat2d by the dimensions in the given vec2
 *
 * @param {mat2d} out the receiving matrix
 * @param {mat2d} a the matrix to translate
 * @param {vec2} v the vec2 to scale the matrix by
 * @returns {mat2d} out
 **/
mat2d.scale = function(out, a, v) {
    var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4], a5 = a[5],
        v0 = v[0], v1 = v[1];
    out[0] = a0 * v0;
    out[1] = a1 * v0;
    out[2] = a2 * v1;
    out[3] = a3 * v1;
    out[4] = a4;
    out[5] = a5;
    return out;
};

/**
 * Translates the mat2d by the dimensions in the given vec2
 *
 * @param {mat2d} out the receiving matrix
 * @param {mat2d} a the matrix to translate
 * @param {vec2} v the vec2 to translate the matrix by
 * @returns {mat2d} out
 **/
mat2d.translate = function(out, a, v) {
    var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3], a4 = a[4], a5 = a[5],
        v0 = v[0], v1 = v[1];
    out[0] = a0;
    out[1] = a1;
    out[2] = a2;
    out[3] = a3;
    out[4] = a0 * v0 + a2 * v1 + a4;
    out[5] = a1 * v0 + a3 * v1 + a5;
    return out;
};

/**
 * Returns Frobenius norm of a mat2d
 *
 * @param {mat2d} a the matrix to calculate Frobenius norm of
 * @returns {Number} Frobenius norm
 */
mat2d.frob = function (a) {
    return(Math.sqrt(Math.pow(a[0], 2) + Math.pow(a[1], 2) + Math.pow(a[2], 2) + Math.pow(a[3], 2) + Math.pow(a[4], 2) + Math.pow(a[5], 2) + 1))
};


export default mat2d;
